PROJECT SUMMARY Astoundingly, about half of approximately 5.7 million persons living with Alzheimer?s disease and related dementias in the United States are undiagnosed. Persons with undiagnosed dementia are living with cognitive impairment that affects everyday activities but has not been detected by patients, families, and/or clinicians. Additionally, in one third of diagnosed patients, they or their families are unaware of a dementia diagnosis. Thus, diagnosis does not always translate to awareness and understanding of a significant condition. Though most individuals with dementia are undiagnosed or unaware, early diagnosis and disclosure is controversial in the absence of disease-modifying treatments. The United States Preventive Services Task Force has not yet found evidence of benefit for early dementia detection on patient outcomes. This proposal seeks to build evidence of whether early diagnosis and awareness, related but distinct concepts, could improve outcomes. A novel approach to identifying potential benefits of early dementia diagnosis is to identify negative outcomes occurring when persons are undiagnosed or unaware. Such outcomes could potentially be prevented through earlier, transparent diagnosis linked to proactive care. This project focuses on health services use, specifically emergency department (ED) visits, hospitalization, hospitalization outcomes, and spending as outcomes that may be affected by lack of dementia diagnosis or awareness. ED visits and hospitalization are common and associated with adverse outcomes in diagnosed dementia; it is not known whether ED and hospitalization rates and outcomes are similar in undiagnosed dementia. Persons with undiagnosed dementia may in fact have higher rates, worse outcomes, and greater spending in the absence of dementia detection, care, and support. To address this hypothesis, the proposal leverages the National Health and Aging Trends Study, a nationally representative cohort of older Americans that identifies participants with probable dementia through a validated interview and assessment-based algorithm. Linked Medicare claims data for 4,311 participants offers the opportunity to examine longitudinal health services outcomes in persons with probable dementia who are undiagnosed or unaware of the diagnosis. Dementia diagnoses will encompass Alzheimer?s disease and related disorders (e.g. vascular, mixed, Lewy body, and frontotemporal dementia). Aim 1 investigates whether dementia diagnosis or awareness is associated with risk of all-cause and potentially preventable ED visits and hospitalizations over four years, comparing undiagnosed versus diagnosed and unaware versus aware of diagnosis. Aim 2 compares annual healthcare spending, and among participants hospitalized, annual hospital length of stay, days at home, and 30-day readmissions by diagnosis and awareness status. Aim 3 identifies predictors of ED visits and hospitalizations among persons undiagnosed or unaware. These aims will contribute to limited knowledge of outcomes in undiagnosed dementia, potential benefits of earlier, transparent diagnosis, and subgroups who may particularly benefit from earlier diagnosis and proactive medical care.